Refractory brick for furnace linings



Patented Mar. 9, 1926.

PATENT orrlca.v

OTTO ARAM, OF PHILADELPHIA, BENNSYLYANIA.

REFBACTORY BRICK FOR FURN'ACE ZILIIBTIINGS..l

Application led September 14, 1922. Serial No. 588,242.

To all whom it may concern Beit known that I, OTTO ARAM, a citizen of the United States,`and a resident of Philadelphia., in the county of Philadelphia and State of Pennsylvania, have invented a new and useful Improvement inf Refractory Bricks for Furnace Linings, of which theJ following is a specification.

' This invention relates to furnaces and particularly to the art of making highly refractory fire brick and furnace linings for y high-temperature furnaces, and has for an Ulv.

object to provide for use in connection with apparatus of the character designated a novel method of treating tire brick which shall make such brick highly resistant to deterioration under high temperatures and to erosion from heated gas movements, and which shall also be relatively non-adhesive with respect to fused silica and other oxides commonly encountered in high-temperature furnace operation. It has for a further object to provide a novel method for lengthening the life of refractory furnace linings and keeping down the co-st of furnace repairs by applying an intimate rotective coating to the interior surfaces o the furnace walls. It has for a still further object to rovide for apparatus of the character designated fire bricks having the surfaces which are to be exposed to the hot products of combustion so treated as to minimize deterioration, Vcheck erosion and" eliminate aecretions thereto of fused ash.

-These and other objects are made more manifest in the further description of my invention reference being had to the accompanying drawings in winch Fig. 1 is a sectional view of a welll known type of `high duty furnace to which m invention may be advantageously ap lie Fig. 2 is an enlarged detail view o, a-section of the furnace wall;v and Fig. 3 is a view in`section of a lire brick treated in accordance with my improved method.

It is a well recognized fact that fire brick having a high percentage of alumina (A1,O) have an extremely hi h fusing point. A brick made entirely o alumina, however, does not have suicient strength foruse in furnace walls, and,consequent1y re brick are commonly made of a mixture composed chiefly of alumina and silica in varying portions. Clinker'. or ashes in a molten state act as iuXes to the refractory material of fire brick and their contents of iron, calcium, and magnesium oxide and alkaline compounds, and react upon the 'fire brick, lowering the fusing point thereof to a. considerable degree, and hence are very destructive to furnace linings. Further, the removal of accretions from furnace lining frequently results in scaling of the exposed surfaces of the brick.

By experimentation, I have found that a coating of aluminum on the exposed surfaces of re brick closes the pores of the refractorymaterial and, when subjected to high heats, forms a surface coating consisting largely` of alumina. This acts as a protective coating for the fire brick, lengthening the life of the refractory furnace lining by keeping off the destructive effects of the fluxes in the ashes, by resisting erosion of the furnace gases and by presenting a surface non-adhesive with respect to the products of combustion. The furnace lining is consequently'kept in good condition attlow cost of maintenance. u

The surface coating of aluminum maybe applied to the fire brlck in any well known process of coating either before the brick are laid up in the furnace wall or after the furnace wall has been constructed. The surface coating should, however, be preferably intimately associated with and com'- pletely fill the pores of the refractory material of the brick.4

A; satisfactory process of coating the brick, particularly where the coating 1s applied to the assembled wall, consists of applying a metallic aluminum coating by means of the well known metal spray gun. The coating thus btained is continuous, may be of any desired depth and is exceedingly intimate. Other processes of coating vmay also be employed. Where the fire brick are treated before being laid u in the furnace wall,I they may be dippe in metallic aluminum, orelectrolytic means for dep0siting the metallic aluminum coating on the fire brick may be employed.

In any of the above processes, the aluminum forms" a continuous coating which enters the pores of the refractory material of the re bricks and serves to anchor the coating u on the brick; There is thus provided a sur ace layer which is free from chipping or scaling, which entirely excludes the contact of the heated furnace products from Contact with the refractory material of the tive layer of aluminum. In Fig. 3, I show a brick to which the coating has been applied. This is one form of the product resulting from thevprocess set forth in this application. As a product, the fire brick may be marketed with a coating of metallic'aluminium onA surfaces which are designed-for eX osure to the interior of the furnace.

t is to be understood that the above described fire bricks and the methods of applying protective coatings thereto are merely illustrative of my inventive idea, and that the inventionis not limited to any specific kind of lire brick or to any special method of coating the brick. The essence of the invention consists in a method of increasing the life of fire brick by providing a protective coating of amaterial having high refractory properties, resistant to erosion and non-adhesive with respect to fused clinker' and ash, and also inthe surface-coated brick and furnace lining which results from this process.

While I have shown my invention in but one form, it will beobvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications, Withoutv depart'ng from the spirit thereof, and I desire, tl erefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specically set -forth in the appended claims.

- What I claim is :-V

1. The method of lengthening the 4life of refractory linings of high temperature furnaces which comprises applying to exposed surfaces of the refractory lining a vsuperficial coating consisting largely of metallic l aluminum.

2. In the art of making refractory bricks, the method which comprises coating an exposed face of a brick with metallic' aluminumfthe brick being composed of a substance Which will combine with the aluminum to form a highly refractory material.

3. In the art of making refractory bricks,

the method which comprises making a fire brick composed largely of alumina and silica, and applying to -an exposed face of the brick an intimateicoating consisting largely of metallipl aluminum.

In testimony v'vhereof, ,I have hereunto subscribed my name this 11th day of September, 1922.

OTTO ARAM. 

